feat(docker-nuke): add restart, daemon polling, and triage summary

This commit is contained in:
David Ibia
2026-07-20 01:19:37 +01:00
parent 252a356426
commit ecd414362a
2 changed files with 222 additions and 2 deletions
+76 -2
View File
@@ -23,9 +23,8 @@ TERM_WAIT=5 # seconds to wait after SIGTERM before SIGKILL
# entry snapshot never knew about, so this must be a real cap, never an
# unbounded loop, or a respawning Docker could hang this tool forever.
KILL_RETRY_ROUNDS=3
# shellcheck disable=SC2034
# shellcheck disable=SC2034 # consumed by Task 8's main() when it calls wait_for_daemon "$RESTART_TIMEOUT"; not yet referenced by this task's code
RESTART_TIMEOUT=90 # seconds to wait for the daemon to come back
# shellcheck disable=SC2034
POLL_INTERVAL=2 # seconds between daemon health polls
SAMPLE_DURATION=2 # seconds of stack sampling per process
SAMPLE_TIMEOUT=10 # hard cap on a single `sample` invocation
@@ -470,6 +469,81 @@ nuke_docker() {
return 0
}
start_docker() {
log "docker-nuke: relaunching Docker Desktop"
open -a Docker >/dev/null 2>&1 || open "$DOCKER_APP" >/dev/null 2>&1 || true
}
# Returns 0 once the daemon answers, 1 if SECONDS elapses first.
#
# The deadline is wall-clock, not a count of sleeps (Fix 2, review round 1).
# docker_healthy can itself cost up to HEALTH_TIMEOUT per call (it runs
# run_timeout "$HEALTH_TIMEOUT" docker info internally), but the old version
# of this loop only ever accumulated POLL_INTERVAL in `waited`, silently
# discounting docker_healthy's own cost every single iteration. Against a
# genuinely wedged daemon that undercount compounds per iteration: with real
# constants (HEALTH_TIMEOUT=6, POLL_INTERVAL=2) an 8s request measured 32s
# wall clock (4x), and the RESTART_TIMEOUT=90 caller could overshoot to
# roughly 6 minutes. Capturing a start time and checking `now - start`
# before each docker_healthy call instead bounds the overshoot to at most
# one in-flight docker_healthy call, never a per-iteration multiplier.
wait_for_daemon() {
local secs="$1"
local start now
start="$(date +%s)"
while :; do
now="$(date +%s)"
if [ "$((now - start))" -ge "$secs" ]; then
return 1
fi
if docker_healthy; then
return 0
fi
sleep "$POLL_INTERVAL"
done
}
# write_summary VERDICT ELAPSED — record the triage payload the user reads
# after recovery. Must never abort the caller, on ANY path (Fix 1, review
# round 1): a no-op when DUMP_DIR is unset, empty, or not a directory (e.g.
# after new_dump_dir failed on a full disk) -- and the write itself is
# guarded too, since the disk can fill AFTER new_dump_dir already created a
# valid DUMP_DIR but BEFORE this function runs; an unwritable or full
# DUMP_DIR at write time is exactly the scenario this tool exists to
# survive. The redirection is nested inside an outer group so the outer
# group's own 2>/dev/null is already in effect before the inner redirection
# is attempted -- a single-level `{ ... } >file 2>/dev/null` does NOT
# suppress bash's own "cannot create" diagnostic, since bash reports that
# failure before the trailing 2>/dev/null on the same command takes effect.
# A write failure is logged via warn and swallowed, never propagated.
write_summary() {
local verdict="$1" elapsed="$2" rc=0
local cf="${CAPTURE_FAILURES:-}"
if [ -z "$cf" ]; then cf=" none"; fi
if [ -z "${DUMP_DIR:-}" ] || [ ! -d "${DUMP_DIR:-}" ]; then
return 0
fi
{
{
printf 'docker-nuke summary\n'
printf '===================\n\n'
printf 'verdict: %s\n' "$verdict"
printf 'elapsed seconds: %s\n' "$elapsed"
printf 'dump directory: %s\n' "$DUMP_DIR"
printf 'capture failures:%s\n' "$cf"
printf '\nTriage hints\n------------\n'
printf '* ps.txt STAT column: U or D means stuck in the kernel, not user space\n'
printf '* disk.txt a full or near-full data volume is a common cause of a wedged daemon -- check free space on the volume backing Docker.raw (df -h) and clear it, or raise the disk image limit in Docker Desktop Settings, before relaunching\n'
printf '* sample-* user-space stacks showing where the daemon was stuck\n'
printf '* logs/ Docker host and vm logs from just before the kill\n'
} >"$DUMP_DIR/summary.txt"
} 2>/dev/null || rc=$?
if [ "$rc" -ne 0 ]; then
warn "docker-nuke: could not write summary to $DUMP_DIR/summary.txt (dump directory unwritable or full)"
fi
return 0
}
log() { printf '%s\n' "$*"; }
warn() { printf '%s\n' "$*" >&2; }
+146
View File
@@ -785,6 +785,152 @@ test_nuke_docker() {
}
test_nuke_docker
printf '\n=== restart and summary ===\n'
test_restart_and_summary() {
local stub="$TMPROOT/stub2" oldpath="$PATH" rc
# DUMP_DIR and CAPTURE_FAILURES are mutated below like PATH is above.
# Restore all three on the way out (Fix 4, review round 1): this is the
# last test block in the file today, so nothing currently leaks, but
# Task 8 appends its own block immediately after this one and would
# silently inherit whatever non-empty DUMP_DIR/CAPTURE_FAILURES this test
# left behind if they were not restored, exactly like PATH and
# HEALTH_TIMEOUT already are elsewhere in this file.
local old_dump_dir="$DUMP_DIR" old_capture_failures="$CAPTURE_FAILURES"
make_docker_stub "$stub" healthy
PATH="$stub:$oldpath"
rc=0; wait_for_daemon 6 || rc=$?
assert_eq "wait_for_daemon returns 0 when healthy" "0" "$rc"
make_docker_stub "$stub" broken
rc=0; wait_for_daemon 4 || rc=$?
assert_eq "wait_for_daemon returns 1 when never healthy" "1" "$rc"
PATH="$oldpath"
DUMP_DIR="$(new_dump_dir)"
CAPTURE_FAILURES=" slow.txt"
write_summary "recovered" "42"
local s
s="$(cat "$DUMP_DIR/summary.txt")"
assert_contains "summary records the verdict" "$s" "recovered"
assert_contains "summary records elapsed time" "$s" "42"
assert_contains "summary records capture failures" "$s" "slow.txt"
assert_not_contains "capture failures line has no double space (Fix 5)" "$s" "failures: "
DUMP_DIR="$old_dump_dir"
CAPTURE_FAILURES="$old_capture_failures"
}
test_restart_and_summary
printf '\n=== wait_for_daemon wall-clock deadline (Fix 2) ===\n'
test_wait_for_daemon_deadline() {
# Regression coverage for the headline wait_for_daemon fix: the old loop
# counted only sleeps, never docker_healthy's own cost, so against a
# daemon that never answers it silently overshoots the requested timeout
# by roughly (HEALTH_TIMEOUT / POLL_INTERVAL)x. HEALTH_TIMEOUT and
# POLL_INTERVAL are scaled down here (2s / 1s instead of the real 6s / 2s)
# purely so this test stays fast; the ratio between them -- the thing that
# actually exposes the bug -- is preserved.
local stub="$TMPROOT/stub3" oldpath="$PATH" rc start elapsed
local old_health="$HEALTH_TIMEOUT" old_poll="$POLL_INTERVAL"
make_docker_stub "$stub" hang
PATH="$stub:$oldpath"
HEALTH_TIMEOUT=2
POLL_INTERVAL=1
start="$(date +%s)"
rc=0; wait_for_daemon 4 || rc=$?
elapsed=$(( $(date +%s) - start ))
assert_eq "wait_for_daemon returns 1 against a hung daemon" "1" "$rc"
# Requested 4s. New deadline-based code bounds the overshoot to at most one
# in-flight docker_healthy call (~2s here), landing around 6s. The old
# counting-sleeps code discounted every docker_healthy call and would land
# around 12s for these constants (see the manual revert-and-measure proof
# run alongside this fix). 8s cleanly separates "new" from "old" while
# leaving headroom for process-spawn/date-granularity jitter.
if [ "$elapsed" -le 8 ]; then
pass "wait_for_daemon honors the wall-clock deadline against a hung daemon (elapsed=${elapsed}s, requested=4s)"
else
fail "wait_for_daemon honors the wall-clock deadline against a hung daemon" \
"elapsed=${elapsed}s, requested=4s, expected <=8s"
fi
HEALTH_TIMEOUT="$old_health"
POLL_INTERVAL="$old_poll"
PATH="$oldpath"
}
test_wait_for_daemon_deadline
printf '\n=== write_summary survives an unwritable DUMP_DIR (Fix 1) ===\n'
test_write_summary_survives() {
# write_summary was previously only ever called with a fresh, valid,
# writable DUMP_DIR (see test_restart_and_summary above), so the
# "unset/missing -> no-op" branch -- the entire reason the guard at the
# top of write_summary exists -- was never exercised, and the write
# itself (the actual Fix 1 bug: an existing-but-now-unwritable-or-full
# DUMP_DIR) had zero coverage at all. Each case below runs write_summary
# in a subshell so a mutated DUMP_DIR/CAPTURE_FAILURES never escapes into
# the rest of the suite.
local rc out
rc=0
out="$(
unset DUMP_DIR CAPTURE_FAILURES
set -u
write_summary "recovered" "1"
printf 'survived\n'
)" || rc=$?
assert_eq "write_summary no-ops when DUMP_DIR is unset (under set -u)" "0" "$rc"
assert_contains "caller survives write_summary with DUMP_DIR unset" "$out" "survived"
rc=0
out="$(
DUMP_DIR=""
write_summary "recovered" "1"
printf 'survived\n'
)" || rc=$?
assert_eq "write_summary no-ops when DUMP_DIR is empty" "0" "$rc"
assert_contains "caller survives write_summary with DUMP_DIR empty" "$out" "survived"
rc=0
out="$(
DUMP_DIR="$TMPROOT/write-summary-does-not-exist"
write_summary "recovered" "1"
printf 'survived\n'
)" || rc=$?
assert_eq "write_summary no-ops when DUMP_DIR does not exist" "0" "$rc"
assert_contains "caller survives write_summary with DUMP_DIR missing" "$out" "survived"
# The actual Fix 1 bug: DUMP_DIR is a real, valid, existing directory (the
# guard's "unset or not a directory" check passes it straight through) but
# is unwritable -- isomorphic to the disk filling between new_dump_dir
# succeeding and write_summary running. set -e is turned on explicitly
# inside the subshell so this reproduces the real script's own
# set -euo pipefail context, not just the harness's relaxed `set +e`.
local ro_dir="$TMPROOT/write-summary-ro"
mkdir -p "$ro_dir"
chmod 555 "$ro_dir"
rc=0
out="$(
set -e
DUMP_DIR="$ro_dir"
CAPTURE_FAILURES=""
write_summary "recovered" "1"
printf 'survived\n'
)" || rc=$?
chmod 755 "$ro_dir"
assert_eq "write_summary returns 0 on an unwritable DUMP_DIR" "0" "$rc"
assert_contains "caller survives write_summary on an unwritable DUMP_DIR (Fix 1)" "$out" "survived"
assert_eq "unwritable DUMP_DIR: no summary.txt was created" "no" \
"$([ -f "$ro_dir/summary.txt" ] && printf 'yes' || printf 'no')"
}
test_write_summary_survives
printf '\n=== summary ===\n'
teardown_tmp
printf 'ran %d, failed %d\n' "$TESTS_RUN" "$TESTS_FAILED"